JPS59190510A - Clamping tool made of ceramic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to fasteners such as bolts and nuts, and particularly to fasteners made of ceramics and suitable for fastening ceramic members.

As a method of joining ceramic members together, there is a method of bolting using ceramic bolts. However, as is well known, ceramics are brittle materials, so if they are tightened too strongly and an impact load is applied, there is a problem in that local stress concentration occurs and the thread grooves are damaged. Indigo ceramic parts are generally not easy to process, and the dimensional accuracy is low for bolts with complex shapes, and the thread grooves formed also have low dimensional accuracy, which exacerbates the problems mentioned above. There is a drawback.

An object of the present invention is to eliminate the drawbacks of the above-mentioned prior art and to provide a ceramic cleft fastener that enables reliable and strong fastening.

In order to achieve all of these objectives, the ceramic fastener of the present invention is such that at least the thread groove portion is coated with a material that becomes soft at temperatures higher than room temperature.

In order to fasten members using the fastener according to the present invention, first, the entire fastener is heated to a predetermined temperature range to soften the material coated in the thread groove or the like. Then, it is fastened in this heated state, and then cooled. Then, the covering material also becomes hard due to cooling, and a strong bond is formed. That's not good. During tightening, the covering material softens and spreads evenly over the gap between the fastened member and fastener, and after cooling and hardening, the fastened member and fastener become tightly integrated. .

Therefore, even if an impact load is applied to the fastening part, local stress concentration is prevented from occurring in the fastener.
The fear of thread groove breakage is completely eliminated, and the bonding strength is greatly improved.

Superplastic alloys are suitable as materials that become soft in a temperature range higher than room temperature, but other materials such as alloys, plastics, gaskets, etc. that are soft in the heating temperature range during bonding may also be used. .

Table 1 shows the composition, elongation, and temperature range showing superplasticity of typical superplastic metals.

The present invention will be explained in more detail below with reference to embodiments shown in the drawings.

FIG. 1 is a side view of a bolt according to an embodiment of the present invention.

The threaded part 1a of this bolt l and the back side 1b of the bolt head
is coated or coated with superplastic alloy. FIG. 2 is a sectional view of a nut according to an embodiment of the present invention, and the thread groove 2a of this nut 2 is also coated or lined with superplastic alloy. Note that the bolt 1 and nut 2 are each made of ceramics.

There are many methods for lining or coating superplastic materials, but methods for fully coating superplastic alloys include electrochemical plating, thermal spraying, and blast bonding. Conceivable. This internal thermal spraying method is a high-temperature flame (for example, an oxygen-propane flame). This method uses an electric arc to melt the alloy, atomizes it with compressed air, and then bonds it to the material by spraying it. The blast bonding method is a method in which a superplastic material powder is blasted onto the surface of a material, and the superplastic flow at that time is utilized to quickly cover the material with the powder by pressure bonding.

The areas to be coated are the parts to be joined and the joining bolts,
It may be applied only to the contact area of the nut, or it may be applied to the entire joint bolt and nut.

FIG. 3 is a sectional view showing a state in which the ceramic plates 3 and 3 are fully joined using the bolts 1 and nuts 2. A hole is made in the ceramic plate 3.3, and the bolt 1 is inserted and the nut 2 is fastened. For this fastening, it is necessary to heat the nut 2 and the ceramic plate 3.3 to a predetermined temperature.

That is, when heated in this way, the nut 2 and the ceramic plate 3 thermally expand, making it easier to insert and tighten the bolt 1, and the superplastic alloy coated on the surface becomes superplastic, reducing the gap between them. When the temperature is lowered, the nut 2 comes to be strongly engaged with the bolt 1. Conversely, when removing the nut 2, the nut 2 can be easily removed by heating the nut 2 to a predetermined temperature. When heating Nut 2, please check the heating temperature. It is necessary to adjust the temperature to the temperature at which the superplastic alloy is most easily deformed, and this serves to prevent local stress concentration at the contact surfaces between the ceramic plates and fill the gap uniformly. In addition, in the bolt 1 shown in Fig. 1, the back side 1b of the bolt head is also lined with superplastic alloy, so when used for joining as shown in Fig. 3, the surface of the ceramic plate 3 and the back side of the bolt head are lined with superplastic alloy. 1b
It also has the effect of making the contact soft and uniform.

FIG. 4 is a sectional view showing a state in which the ceramic plate 4 and the thick ceramic member 5 are joined together using all the bolts 1. That is, a through hole 4a and a screw hole 5a are provided in the ceramic plate 4 and the ceramic member 5, respectively, and the bolt 1 is fully tightened. In this embodiment as well, the bolt 1 and the ceramic member 5 are firmly joined, and the contact between the ceramic plate 4 and the back side 1b of the bolt head of the bolt 1 is uniformly softened. In this embodiment as well, when tightening the bolt 1, tightening can be facilitated by heating the ceramic member 5 to a temperature range that exhibits the superplastic behavior of the superplastic alloy that has been lined in advance. At the same time, the contact surface exhibits superplastic behavior, preventing the generation of local stress and increasing the bonding strength after the temperature of the ceramic member 5 has decreased. Further, if the ceramic plate 4 is heated, the bolt 1 can be inserted easily.

In this embodiment, the thread groove of the threaded hole 5a formed in the ceramic member 5 may also be lined with a superplastic alloy.

In each of the above embodiments, the bolt 1 and nut 2 are lined with a superplastic alloy, but this may be made of other metals, plastics, lubrication, gaskets, etc. that become soft within a predetermined temperature range.

Furthermore, in the present invention, the material of the ceramics that make up the entire bolt, nut, etc. is not particularly limited, and it is clear that various oxides, nitrides, carbides, or compositions of combinations of these can be used.

The fastener of the present invention as described above has at least its thread groove fully coated with a material that becomes soft within a predetermined temperature range, and has high bonding strength and high resistance to impact loads. This enables reliable and strong bonding.

[Brief explanation of the drawing]

Fig. 1 is a side view of a bolt according to an embodiment of the present invention, Fig. 2 is a sectional view of the same nut, Fig. 3 is a sectional view of a state in which a ceramic plate 3 is joined, and Fig. 4 shows a different state of joining. FIG. 1...Ceramic bolt, 2...Ceramic nut. − Agent Tatsuyuki Unuma (and 1 other person)

Claims (3)

[Claims] (1) A ceramic fastener having a carved thread groove, at least the thread groove being entirely coated with a substance that becomes softer than the fastener in a temperature range higher than room temperature. . (2) The ceramic fastener according to claim 1, wherein the fastener is a bolt or a nut. (3) The ceramic fastener according to claim 1 or 2, wherein the soft material is a superplastic alloy.